The Invisible JavaScript Backdoor

A cleverly disguised (and frightening) nearly undetectable exploit. Wolfgang Ettlinger poses the question: What if a backdoor is literally invisible, evading even the most thorough code reviews?

The image below highlights the exploit within the code. Even with close inspection, it's easy to overlook. This is because the exploit avoids linting errors and doesn't disrupt syntax highlighting.

The execution method is subtle: The hardcoded commands, along with any user-supplied parameters, are passed as elements within an array to the exec function. This function then executes the OS commands.

The Cambridge team's proposed solution addresses this vulnerability: restricting Bidirectional Unicode characters. However, as this example demonstrates, homoglyph attacks and invisible characters present a significant ongoing threat.

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